The Influence of Child-Produced Speech on Infant Language Development

Project Summary
Early language skills have been linked to experience with language in the real world. However, the majority of
this research has focused on infant’s experiences with adult caregivers. The majority of children, however,
hear language from other children, in addition to adult caregivers, whether that be in the home, on the
playground, or in childcare settings, to name a few. In fact, 80% of US children have at least one sibling
(Census data, 2010), and out pilot data suggests that infants with siblings hear speech from children every
49s. However, having an older sibling seems to have a negative effect on language development, with younger
siblings showing slower language development than first-born children. The proposed work investigates how
speech from young children may influence language development, in an effort to understand why language
development differs for later- relative to first-born children. Its overall objective is to establish how infants
process speech from children relative to adults, whether speech from children differs systematically in content
and complexity, and how processing of child-produced speech and the content of child-produced speech
influence language development.
Aim 1 tests two central facets of speech perception: preferences for speech produced by children vs. adults,
and word recognition for speech produced by children vs. adults. Aim 2 collects and fully transcribes a corpus
of play sessions between a parent, sibling, and young infant, to understand what older siblings say in the
presence of younger infants, and how that differs from the input their receive from adult caregivers. Aim 3 asks
whether infant’s preference for or processing of child-produced speech from Aim 1 relates to their vocabulary
growth at 18 months, and whether infant’s own experiences with child-produced speech during play sessions
from Aim 2 also shapes vocabulary growth at 18 months.
Results from this set of Aims will provide important information about the role of child-produced speech in early
language development. Understanding whether speech from young children is preferentially attended to by
infants, and whether it provides different content for infants to learn from will inform how we can differentially
support language development for infants who may have different experiences with child-produced speech,
which is likely to vary across cultures, linguistic backgrounds, and socioeconomic status.

Grant Number: 5R21HD115222-02
NIH Institute/Center: NIH
Principal Investigator: Federica Bulgarelli